Biodegradable resin composition and molded object thereof

ABSTRACT

A resin composition (AA) comprising an aliphatic polyester or aliphatic polyamide (component (A)), a plastic having a melting point or glass transition temperature (Tg) of −10° C. or more (component (B)) and a radical generating agent (C), wherein the compounding ratio of the component (A), the component (B) and the radical generating agent (C), based on the total weight thereof, is: 1 to 98.995% by weight of the component (A), 98.995 to 1% by weight of the component (B), and 0.005 to 5% by weight of the radical generating agent (C), and an aliphatic unsaturated polybasic acid (a) is contained in the polymer constituent of the component (A) and/or the component (B). The resin composition is suitable as a starting material of biodegradable material which maintains transparency, is free of bleeding of a plasticizer, is endowed with flexibility and has other advantageous characteristics so that it can be used in various fields.

TECHNICAL FIELD

The present invention relates to a resin composition with improvementsin physical properties such as flexibility and transparency and inparticular to a biodegradable resin composition.

BACKGROUND ART

Biodegradable plastics are plastics, which can, similar to usualplastics, be used as thermoplastic resin and are decomposed into waterand carbon dioxide after use by the action of microorganisms etc. Asconsciousness of environmental problems is increased in recent years,many biodegradable plastics have been developed. For example, a resincomposition based on polylactic acid or a lactic acid/other hydroxycarboxylic acid copolymer is disclosed as biodegradable plastics in JP-A6-340753.

Many biodegradable plastics including polylactic acid exhibit highstrength, modulus of elasticity, and rigidity, but suffer from adisadvantage of lack of flexibility. Accordingly, the biodegradableplastics were not suitable for uses requiring flexibility wherepolyethylene, polypropylene, soft polyvinyl chloride, etc. are widelyused.

Generally, a method of adding a plasticizer is known as a method ofrendering resin flexible. For example, JP-A4-335060 discloses acomposition having a plasticizer added to polylactic acid. Examples ofthe plasticizer include diisobutyl adipate, dioctyl sebacate etc.However, the plasticizing effect of these plasticizers is low and cannotachieve sufficient flexibility. When these plasticizers are used, theplasticizers are bled just after molding or with time to changeflexibility and transparency. When the biodegradable plastics arepolylactic acid of particularly high rigidity, a method of rendering theplastics flexible by blending other relatively flexible biodegradableplastics is also disclosed. For example, JP-A8-245866 and JP-A 9-111107disclose a method of blending polybutylene succinate, polyethylenesuccinate, polylactone etc. as relatively flexible biodegradableplastics with polylactic acids. JP-A2001-26658 discloses a compositionhaving a plasticizer and a radical generating agent added to polylacticacid. However, a large amount of the biodegradable plastics should beadded to confer sufficient flexibility on polylactic acid, resulting indeterioration of heat resistance and transparency as features ofpolylactic acid.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a resin compositionusable preferably as a biodegradable material having excellentflexibility, heat resistance and transparency and hardly changingphysical properties with time without bleeding low-molecular compoundssuch as a plasticizer.

In view of the prior art described above, the present inventors madeextensive study, and as a result they found that biodegradable plasticscan be rendered flexible effectively by mixing them with an aliphaticpolyester having a glass transition temperature of 25° C. or less andcontaining a radial generating agent and its decomposed product,preferably an aliphatic unsaturated poly basic acid as a polymerconstituent, and further reacting an unsaturated bond of the aliphaticpolyester, and the present invention was thereby arrived at.

That is, the present relates to a resin composition (AA) comprising analiphatic polyester or aliphatic polyamide (component (A)), a plastichaving a melting point or glass transition temperature (Tg) of −10° C.or more (component (B)) and a radical generating agent (C),

-   -   wherein the compounding ratio of the aliphatic polyester or        aliphatic polyamide (component (A)), the plastic having a        melting point or glass transition temperature (Tg) of −10° C. or        more (component (B)) and the radical generating agent (C), based        on the total weight thereof, is:    -   1 to 98.995% by weight of the aliphatic polyester or aliphatic        polyamide (component (A)),    -   98.995 to 1% by weight of the plastic having a melting point or        glass transition temperature (Tg) of −10° C. or more (component        (B)), and    -   0.005 to 5% by weight of the radical generating agent (C), and    -   when the component (A) is an aliphatic polyester, the        compounding ratio of repeating units in the molecule, based on        the number of total repeating units in the molecule (assuming        that the number of total repeating units in the molecule is 100        mol %), is:    -   0 to 50 mol % repeating unit (a) having an aliphatic unsaturated        bond,    -   0 to 51 mol % polyvalent alcohol unit (b),    -   0 to 51 mol % saturated polybasic acid unit (c), and    -   0 to 80 mol % aliphatic hydroxycarboxylic acid or lactone        compound unit (d).

Further, the present invention relates to:

-   -   a resin modifier comprising the resin composition (AA),    -   a resin composition (BB) comprising 1 to 50% by weight of the        resin composition (AA) and 50 to 99% by weight of a        biodegradable resin (D), and    -   a molded article of the resin composition (AA) or (BB)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention is described in detail.

The present invention relates to a resin composition (AA) comprising analiphatic polyester or aliphatic polyamide (component (A)), a plastichaving a melting point or glass transition temperature (Tg) of −10° C.or more (component (B)) and a radical generating agent (C),

-   -   wherein the compounding ratio of the component (A), the        component (B) and the radical generating agent (C), based on the        total weight thereof, is:    -   1 to 98.995% by weight of the component (A),    -   98.995 to 1% by weight of the component (B), and    -   0.005 to 5% by weight of the radical generating agent (C), and        an aliphatic unsaturated polybasic acid (a) is contained in the        polymer constituent of the component (A) and/or the component        (B); a resin composition (BB) obtained therefrom; and a molded        article obtained therefrom. Hereinafter, the respective        components (A), (B), (C) and (D), the resin compositions (AA)        and (BB), and the molded article are described.        [Aliphatic Polyester or Aliphatic Polyamide (component (A))]

The component (A) comprises an aliphatic polyester or an aliphaticpolyamide and may be a mixture of the aliphatic polyester and aliphaticpolyamide. The glass transition temperature (Tg) of the component (A) is25 to −90° C., preferably 0 to −80° C., more preferably −30 to −80° C.When the component (A) has a melting point (Tm), the Tm is preferably25° C. or less.

When the component (A) is an aliphatic polyester, the compounding ratioof total repeating units in the aliphatic polyester (component (A))molecule, based on the number of total repeating units in the molecule,is:

-   -   0 to 50 mol % aliphatic unsaturated polybasic acid (a),    -   0 to 51 mol % aliphatic polyvalent alcohol (b),    -   0 to 51 mol % aliphatic saturated polybasic acid (c), and    -   0 to 80 mol % aliphatic hydroxycarboxylic acid (d). The        compounding ratio is preferably as described in (a) to (d)        below.

The aliphatic polyester having an aliphatic unsaturated bond is the onehaving 0 to 50 mol % repeating unit having an aliphatic unsaturatedbond, based on total repeating units in the molecule, and having a glasstransition temperature (Tg) of 25 to −90° C., preferably 0 to −80° C.,more preferably −30 to −80° C., and having a weight-average molecularweight (Mw) of 1000 to 300,000. When the content of the aliphaticunsaturated bond is too low, crosslinking reaction does not sufficientlyoccur, thus failing to exhibit a sufficient effect on modification ofbiodegradable plastics. On the other hand, when the content of thealiphatic unsaturated bond is too high, excessive crosslinkage occurs todeteriorate physical properties of biodegradable plastics significantly.

The aliphatic polyester having an aliphatic unsaturated bond isdesirably an amorphous one whose melting point cannot be measured at atemperature substantially higher than room temperature. When thecrystallinity of the aliphatic polyester is high, the compatibilitythereof with biodegradable plastics is lowered and no sufficientplasticizing effect may be obtained.

The presence or absence of crystallinity can be confirmed by measurementmeans such as X-ray diffraction or a differential scanning calorimeter.

A too low molecular weight of the aliphatic polyester having analiphatic unsaturated bond is not preferable because physical propertiesof the resin composition are changed with time after molding, orbleeding of the aliphatic polyester occurs easily. On the other hand, atoo high molecular weight is not preferable either because meltviscosity is increased so that the aliphatic polyester is hardly mixedwith biodegradable plastics. Generally, the weight-average molecularweight of the aliphatic polyester having an aliphatic unsaturated bondis preferably 1,000 to 300,000, more preferably 2,000 to 100,000, asdetermined by GPC (for example in a chloroform solvent system)

[Method of Producing the Aliphatic Polyester (Aliphatic Polyester,Component (A))]

The method of producing the aliphatic polyester, preferably thealiphatic polyester having an aliphatic unsaturated bond (component (A))is not particularly limited. The method is described for example in JP-A10-1536 and JP-A 11-60662. For example, the aliphatic polyester can beproduced by reaction of lactones, lactide, glycollide andhydroxycarboxylic acids, by reaction of polyvalent alcohols withpolybasic acids, etc., preferably by reaction of polyvalent alcoholswith polybasic acids. An aliphatic unsaturated bond can be contained inthe aliphatic polyester by the coexistence of lactones,hydroxycarboxylic acids, polyvalent alcohols or polybasic acids havingan aliphatic unsaturated bond, as at least one component of thelactones, hydroxycarboxylic acids, polyvalent alcohols, and polybasicacids used in the reaction.

Among these, polybasic acids having an aliphatic unsaturated bond areparticularly preferable.

The aliphatic polyester (aliphatic polyester, component (A)) having thealiphatic hydroxycarboxylic acid (d) can be produced preferably by usingan aliphatic unsaturated polybasic acid as the repeating unit (a) havingan aliphatic unsaturated bond, to obtain a copolymer (ab) of thealiphatic unsaturated polybasic acid and the aliphatic hydroxycarboxylicacid (d), and then copolymerizing the copolymer (ab) with the polyvalentalcohol unit (b) and the saturated polybasic acid unit (c).

[Repeating Unit (a) Having an Aliphatic Unsaturated Bond Constitutingthe Aliphatic Polyester (Aliphatic Polyester, Component (A))]

The compound having an aliphatic unsaturated bond is preferably analiphatic unsaturated polybasic acid. Examples of the aliphaticunsaturated polybasic acid used in the present invention include fumaricacid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride,citraconic acid and citraconic anhydride.

The amount of the aliphatic unsaturated polybasic acid in the aliphaticpolyester (component (A)) molecule in the present invention is 0 to 50mol %, preferably 0.1 to 20 mol %, more preferably 0.5 to 10 mol %. Inthe present invention, the aliphatic polyester having an aliphaticunsaturated bond may contain a small amount of urethane bond. Thecontent of the urethane bond is less than about 10 mol % based on totalrepeating units in the molecule. In the present invention, the aliphaticpolyester having an aliphatic unsaturated bond may be obtained byextending the aliphatic polyester obtained by the method describedabove, by a binding agent such as diisocyanate compound.

[Polyvalent Alcohol Unit (b) Constituting the Aliphatic Polyester(Aliphatic Polyester, Component (A))]

Generally, the aliphatic polyvalent alcohol used in the presentinvention is preferably an aliphatic divalent alcohol. Examples of thepolyvalent alcohol used in the present invention include, for example,ethylene glycol, diethylene glycol, triethylene glycol, polyethyleneglycol, propylene glycol, dipropylene glycol, ethylene glycol/propyleneglycol copolymer, 1,3-butane diol, 1,4-butane diol, 3-methyl-1,5-pentanediol, 1,6-hexane diol, 1,9-nonane diol, neopentyl glycol,polytetramethylene glycol etc. Further, a small amount of amultifunctional (trivalent or more) alcohol such as glycerin,trimethylol propane etc. may also be contained. Among these compounds,the polyethylene glycol represented by the chemical formula (1) and/orthe polytetramethylene glycol represented by the chemical formula (2)are preferable.HO—(—CH₂CH₂O)_(n)—H   (1)(2≦n≦10)HO—(—CH₂CH₂CH₂CH₂O—)_(n)—H   (2)(1≦n≦10)

In the present invention, the amount of the polyvalent alcohol in thealiphatic polyester (component (A)) molecule is 0 to 51 mol %,preferably 10 to 51 mol %, more preferably 20 to 51 mol %.

[Saturated Polybasic Acid Unit (c) Constituting the Aliphatic Polyester(Aliphatic Polyester, Component (A))]

Generally, the aliphatic saturated polybasic acid used in the presentinvention is preferably an aliphatic dibasic acid. Examples of thealiphatic saturated polybasic acid include, for example, oxalic acid,malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,suberic acid, azelaic acid, sebacic acid, and esters and anhydridesthereof. Further, a small amount of a trifunctional or more polybasicacid such as butane tetracarboxylic acid may also be contained. Theamount of the saturated polybasic acid in the aliphatic polyester(component (A)) molecule in the present invention is 0 to 51 mol %,preferably 10 to 51 mol %, more preferably 20 to 51 mol %.

[Aliphatic Hydroxycarboxylic Acid (d) Constituting the AliphaticPolyester (Aliphatic Polyester, Component (A))]

The aliphatic hydroxycarboxylic acid used in the present invention isnot particularly limited insofar as it is a hydroxy-containingcarboxylic acid and/or lactone compound. Specific examples includealiphatic hydroxycarboxylic acids such as glycolic acid(2-hydroxyethanoic acid), lactic acid (2-hydroxypropanoic acid),tartaric acid, citric acid, malic acid, 2-hydroxybutanoic acid,2-hydroxypentanoic acid, 2-hydroxyhexanoic acid, 2-hydroxyheptanoicacid, 2-hydroxyoctanoic acid, 2-hydroxy-2-methylpropanoic acid,2-hydrdoxy-2-methylbutanoic acid, 2-hydroxy-2-ethylbutanoic acid,2-hydroxy-2-methylpentanoic acid, 2-hydroxy-2-ethylpentanoic acid,2-hydroxy-2-propylpentanoic acid, 2-hydroxy-2-butylpentanoic acid,2-hydroxy-2-methylhexanoic acid, 2-hydroxy-2-ethylhexanoic acid,2-hydroxy-2-propylhexanoic acid, 2-hydroxy-2-butylhexanoic acid,2-hydroxy-2-pentylhexanoic acid, 2-hydroxy-2-methylheptanoic acid,2-hydroxy-2-ethylheptanoic acid, 2-hydroxy-2-propylheptanoic acid,2-hydroxy-2-butylheptanoic acid, 2-hydroxy-2-pentylheptanoic acid,2-hydroxy-2-hexylheptanoic acid, 2-hydroxy-2-methyloctanoic acid,2-hydroxy-2-ethyloctanoic acid, 2-hydroxy-2-propyloctanoic acid,2-hydroxy-2-butyloctanoic acid, 2-hydroxy-2-pentyloctanoic acid,2-hydroxy-2-hexyloctanoic acid, 2-hydroxy-2-heptyloctanoic acid,3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 3-hydroxypentanoicacid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoicacid, 3-hydroxy-3-methylbutanoic acid, 3-hydroxy-3-methylpentanoic acid,3-hydroxy-3-ethylpentanoic acid, 3-hydroxy-3-methylhexanoic acid,3-hydroxy-3-ethylhexanoic acid, 3-hydroxy-3-propylhexanoic acid,3-hydroxy-3-methylheptanoic acid, 3-hydroxy-3-ethylheptanoic acid,3-hydroxy-3-propylheptanoic acid, 3-hydroxy-3-butylheptanoic acid,3-hydroxy-3-methyloctanoic acid, 3-hydroxy-3-ethyloctanoic acid,3-hydroxy-3-propyloctanoic acid, 3-hydroxy-3-butyloctanoic acid,3-hydroxy-3-pentyloctanoic acid, 4-hydroxybutanoic acid,4-hydroxypentanoic acid, 4-hydroxyhexanoic acid, 4-hydroxyheptanoicacid, 4-hydroxyoctanoic acid, 4-hydroxy-4-methylpentanoic acid,4-hydroxy-4-methylhexanoic acid, 4-hydroxy-4-ethylhexanoic acid,4-hydroxy-4-methylheptanoic acid, 4-hydroxy-4-ethylheptanoic acid,4-hydroxy-4-propylheptanoic acid, 4-hydroxy-4-methyloctanoic acid,4-hydroxy-4-ethyloctanoic acid, 4-hydroxy-4-propyloctanoic acid,4-hydroxy-4-butyloctanoic acid, 5-hydroxypentanoic acid,5-hydroxyhexanoic acid, 5-hydroxyheptanoic acid, 5-hydroxyoctanoic acid,5-hydroxy-5-methylhexanoic acid, 5-hydroxy-5-methylheptanoic acid,5-hydroxy-5-ethylheptanoic acid, 5-hydroxy-5-methyloctanoic acid,5-hydroxy-5-ethyloctanoic acid, 5-hydroxy-5-propyloctanoic acid,6-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 6-hydroxyoctanoic acid,6-hydroxy-6-methylheptanoic acid, 6-hydroxy-6-methyloctanoic acid,6-hydroxy-6-ethyloctanoic acid, 7-hydroxyheptanoic acid,7-hydroxyoctanoic acid, 7-hydroxy-7-methyloctanoic acid and8-hydroxyoctanoic acid, as well as esters, oligomers and cyclic lactonesderived therefrom.

Specific examples of the cyclic lactones include cyclic esterintermediates of hydroxycarboxylic acids, for example lactide as acyclic lactic acid dimer, glycollide as a cyclic glycolic acid dimer,and ε-caprolactone as cyclic 6-hydroxycaprolate, as well asβ-propiolactone, γ-butyrolactone, δ-valerolactone etc. Preferableexamples include lactic acid, glycolic acid, 3-hydroxybutyric acid,4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid and6-hydroxycapronic acid, among which lactic acid is preferable for thetransparency of the resulting polyhydroxycarboxylic acid.

Two or more of these hydroxycarboxylic acids may be simultaneously used.

In a hydroxycarboxylic acid having asymmetric carbon in the molecule,such as lactic acid, a mixture of equal amounts of D- andL-hydroxycarboxylic acids (racemate) occurs, and either D- orL-hydroxycarboxylic acid can be used. L-lactic acid is particularlypreferable.

The amount of the aliphatic hydroxycarboxylic acid in the aliphaticpolyester (component (A)) molecule in the invention is 0 to 80 mol %,preferably 10 to 70 mol %, more preferably 30 to 60 mol %.

[Aliphatic Polyamide (Component (A))]

The aliphatic polyamide (component (A)) includes polyamides such aspolycapramide (nylon-6), poly-(o-aminoheptanoic acid (nylon-7),poly-ω-aminonanoic acid (nylon-9), polylauryllactam (nylon-12),polyethylene diamine adipamide (nylon-2, 6), polytetramethyleneadipamide (nylon-4, 6), polyhexamethylene adipamide (nylon-6, 6),polyhexamethylene sebacamide (nylon-6, 10), polyhexamethylene dodecamide(nylon-6, 12), polyoctamethyleneadipamide (nylon-8, 6),polydecamethylene adipamide (nylon-10, 8), or caprolactam/lauryllactamcopolymer (nylon-6/12), caprolactam/o-aminononanoic acid copolymer(nylon 6/9), caprolactam/hexamethylene diammonium adipate copolymer(nylon-6/6, 6), lauryllactam/hexamethylene diammonium adipate copolymer(nylon-12/6, 6), hexamethylene diammonium adipate copolymer (nylon-2,6/6, 6), caprolactam/hexamethylene diammoniumadipate/hexamethylenediammonium sebacate copolymer (nylon-6, 6/6, 10), ethylene diammoniumadipate/hexamethylene diammoniumadipate/hexamethylene diammoniumsebacate copolymer (nylon-6/6, 6/6, 10), polymethaxylene adipamide(MXD6), hexamethylene terephthalamide/hexamethylene isophthalamidecopolymer (nylon 6I-6T) etc.

The polyamide includes polyamino acids and derivatives thereof, forexample polymers based on amino acids, such as polysuccinic imide,polyaspartic acid, polyglutamic acid and polylysine, crosslinkedproducts of these polymers, and derivatives chemically modified with apendant group etc. The repeating unit in the main-chain fundamentalskeleton of the polyamino acid derivative may be a copolymer composed oftwo or more amino acid structural units. The copolymer may be a blockcopolymer, a random copolymer or a graft copolymer.

The polyamino acid derivative is for example a polymer containing atleast one member selected from the group consisting of polysuccinicimide, polyaspartic acid (salt), polyglutamic acid (salt), crosslinkedpolysuccinic imide, crosslinked polyaspartic acid (salt) and crosslinkedpolyglutamic acid (salt). The “acid (salt)” means an acid and/or a salt.

The starting material of the polyamino acid derivative includes, forexample, aspartic acid, 19 kinds of essential amino acids excludingaspartic acid, as well as amino acids and amino acid derivatives such asL-ornithine, a series of a-amino acids, β-alanine, γ-aminobutyric acid,neutral amino acids, acidic amino acids, ω-esters of acidic amino acid,basic amino acids, N-substituted basic amino acids, and asparticacid-L-phenyl alanine dimer (aspartame), and aminosulfonic acids such asL-cysteine. Isomers of these starting materials are not particularlylimited. For example, α-amino acid may be L-, D- or DL-amino acid.

The structure of the main-chain moiety of the polyamino acid derivativemay have a linear structure or a branched structure. In the main-chainfundamental skeleton of polyaspartic acid or crosslinked polyasparticacid as one polyamino acid derivative, the amide bond in the main chainis an α- or β-bond. Usually, both α- and β-bonds occur in thepolyaspartic acid structure, and in the present invention, the mode ofbinding is not particularly limited.

[Plastic having a Melting Point or Glass Transition Temperature (Tg) of−10° C. or more (Component (B))]

The plastic having a melting point or glass transition temperature (Tg)of −10° C. or more (component (B)) in the present invention refers tothermoplastic resin having a melting point or glass transition point(Tg) of preferably 25° C. or more and a weight-average molecular weight(Mw) of 1000 or more and exhibiting the highest decomposition degree of60% or more in a biodegradation test such as OECD301C, JIS K6950, JISK6951, or JIS K6953, as well as a resin composition based thereon. Thecomponent (B) may have an aliphatic unsaturated bond.

Specific examples include polylactic acid, polyglycolic acid, lacticacid-glycolic acid copolymer, polyhydroxy butyrate, polybutylenesuccinate, polyvinyl alcohol, cellulose acetate, polyethylene succinate,polycaprolactone, polybutylene succinate adipate modification,polybutylene succinate carbonate modification, polybutyreneadipate/terephthalate, starch etc. As the biodegradable plastics in thepresent invention, lactic acid-based polyesters containing at least 5mol % lactic acid unit as a polymer constituent are preferably used.Among the lactic acid-based polyesters, polylactic acid is particularlypreferably used.

[Radial Generating Agent (C)]

The radical generating initiator (C) used in the present inventionincludes known benzoyl peroxides, for example peroxides such asp-chlorobenzoyl peroxide, lauroyl peroxide, acetyl peroxide, di-t-butylperoxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane,1,1-t-butylperoxy-3,3,5-trimethyl cyclohexane, t-butyl peroxy pivalate,t-butylperoxy-2-ethyl hexanoate, t-butyl peroxy benzoate, bis(4-t-butylcyclohexyl)peroxy dicarbonate, diisopropyl peroxy dicarbonate andt-butyl peroxy isopropyl carbonate, as well as azo compounds such asazobisisobutyronitrile. These radical generating agents are used singlyor as a mixture of two or more thereof. These radical generating agentsare used in a ratio of 0.005-5 parts by weight, preferably 0.01-3 partsby weight, to 100 parts by weight of the aliphatic polyester oraliphatic polyamide having an aliphatic unsaturated bond. In the case ofthermal crosslinking reaction, the temperature and time for thecrosslinking reaction are selected suitably depending on the amount ofthe biodegradable plastics mixed, the type of the radical generatingagent used, etc. A crosslinking aid can also be used in combination withthe radical generating agent. The crosslinking aid can be exemplified byallyl compounds such as triallyl cyanurate and triallyl isocyanurate,methacrylate compounds such as ethylene glycol dimethacrylate andtrimethylol propane trimethacrylate, and vinyl-containing compounds suchas divinyl benzene.

[Resin Composition (AA)]

The resin composition (AA) comprises an aliphatic polyester or aliphaticpolyamide (component (A)), a plastic having a melting point or glasstransition temperature (Tg) of −10° C. or more (component (B)), and aradical generating agent (C), wherein the compounding ratio thereof,based on the total weight thereof, is 1 to 98.995%, preferably 20 to80%, more preferably 40 to 60% by weight of the component (A), 98.995 to1%, preferably 20 to 80%, more preferably 40 to 60% by weight of thecomponent (B), and 0.005 to 5%, preferably 0.02 to 2%, more preferably0.05 to 0.5% by weight of the radical generating agent (C).

[Method of Producing the Resin Composition (AA)]

The resin composition (AA) of the present invention can be obtained bymixing the aliphatic polyester or aliphatic polyamide (component (A)),the plastic having a melting point or glass transition temperature (Tg)of −10° C. or more (component (B)) and the radical generating agent (C),and can be made excellently compatible by a crosslinking reaction withthe radical generating agent during or after mixing.

It is estimated that the crosslinking reaction occurs not only in thecomponent (A) or (B) but also between the components (A) and (B). Whenthe component (A) and/or the component (B) has an aliphatic unsaturatedbond, the crosslinking reaction occurs mainly in the unsaturated bondcontained in the structure of the component (A) or (B). Particularlywhen the biodegradable plastic is a lactic acid-based polyester, acrosslinking reaction involving withdrawal of methine hydrogen in thelactic acid unit easily occurs. When crosslinking occurs between thecomponents (A) and (B), a copolymer having both the components (A) and(B) is formed, and this copolymer enhances the ability of both thecomponents to be compatible with each other in the resin composition.

Generally, different kinds of polymers are hardly rendered compatiblewith each other, and are generally hardly uniformly mixed except for fewexceptions. Accordingly, even if a merely flexible or liquid polymer(for example aliphatic polyester not having an aliphatic unsaturatedbond) is mixed as a plasticizer with biodegradable plastics, noexcellent plasticizing effect can be achieved, and thus thebiodegradable plastics are rendered opaque and the plasticizer isseparated and bled. On the other hand, the resin composition of theinvention after crosslinking reaction between the aliphatic polyesterhaving an aliphatic unsaturated bond and the biodegradable plastic givesa molded article with improvements in flexibility excellent particularlyin transparency and free from bleeding of the plasticizer for the abovereason.

The method of crosslinking the resin composition (AA) in the presentinvention is not particularly limited. The crosslinking reaction iscaused mainly by heat, light, ultraviolet rays and electron rays. Aninitiator generating radicals and/or a sensitizer can be used to causethe crosslinking reaction easily. The initiator and sensitizer can bethose known in the art. For crosslinking by heating, a method ofgranulation with a single- or twin-screw extruder is preferable, and acrosslinking aid can be used together with the radical generating agent.

In the crosslinking reaction with light such as ultraviolet rays, thesensitizer used is not particularly limited. Examples include known4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone,4-t-butyl-trichloroacetophenone, diethoxyacetophenone,2-hydroxy-2-methyl-1-phenylpropan-1-one,1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1,benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropylether, benzoin isobutyl ether, benzyl methyl ketal, benzophenone,benzoylbenzoic acid, methyl benzoyl benzoate, 4-phenyl benzophenone,hydroxybenzophenone, 4-benzoyl-4′-methyl diphenyl sulfide,3,3′-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone,2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diisopropyl thioxanthone,1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl) oxime,2,4,6-trimethylbenzoyldiphenylphosphine oxide, methylphenyl glyoxylate,camphor quinone, dibenzosuberone, 2-ethylanthraquinone,4′,4″-diethylisophthalophenone, and3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone. These are usedsingly or as a mixture of two or more thereof. These sensitizers areused in a ratio of 0.005-5 parts by weight, preferably 0.01-3 parts byweight, to 100 parts by weight of the aliphatic polyester or aliphaticpolyamide having an aliphatic unsaturated bond. Further, theabove-mentioned radical generating initiator can also be used incombination. The crosslinking reaction with gamma rays does notparticularly require the radial generating agent.

[Resin Modifier Comprising the Resin Composition (AA)]

When the resin composition (AA) is used as a resin modifier, the resincomposition (AA) comprises the components (A) and (B) and the radicalgenerating agent (C), wherein the amount of the component (A) ispreferably 20 to 80% by weight, more preferably 40 to 60% by weight, theamount of the component (B) is preferably 20 to 80% by weight, morepreferably 40 to 60% by weight, and the amount of the radical generatingagent (C) is preferably 0.02 to 2% by weight, more preferably 0.05 to0.5% by weight, based on the total weight.

[Resin Composition (BB)]

The resin composition (BB) comprises 1 to 50%, preferably 10 to 45%,more preferably 20 to 40% by weight of the resin composition (AA) and 50to 99%, preferably 55 to 90%, more preferably 60 to 80% by weight of thebiodegradable resin (D).

In this case, the resin composition (AA) is used as a resin modifier forthe biodegradable resin (D), and upon addition to the biodegradableresin (D), improves flexibility, heat resistance and transparency. Thebiodegradable resin (D) is used in the same meaning as that of thecomponent (B) and may be the same as or different from the component (B)constituting the resin composition (AA). The resin composition (BB)contains at least 50% by weight of polylactic acid, more preferably atleast 60% by weight of polylactic acid.

When the resin composition (BB) contains at least 60% by weight ofpolylactic acid, the MFR (190° C., loading 2.16 kg) and swell ratio (SR)of the resin composition (BB) satisfy the following relationship(relationship 3) when the MFR (190° C., loading 2.16 kg) is lower than50 g/10 min.SR≧−0.6 log (MFR)+1.8   (3)[Additives]

Depending on purposes (improvements for example in moldability,fabrication, degradation, tensile strength, heat resistance, shelfstability, weatherability etc.), various additives (plasticizers,antioxidants, UV absorbers, heat stabilizers, flame retardants, internalreleasing agents, inorganic additives, antistatic agents, surfacewetting improvers, combustion aids, pigments, lubricants, naturalproducts etc.) can be added to a molded article comprising the resincomposition of the present invention. For example, inorganic additivesand lubricants (aliphatic carboxylic amides) can also be added forpreventing blocking or improving sliding properties of film and sheet inT-die extrusion molding.

The inorganic additives include silica, calcium carbonate, talc, kaolin,kaolinite, titanium oxide, zinc oxide etc., among which silica andcalcium carbonate are particularly preferable. These can be used singlyor as a mixture of two or more thereof. The organic additives includestarch, derivatives thereof, cellulose and derivatives thereof, pulp andderivatives thereof, paper and derivatives thereof, wheat flour, soybeanfiber, bran, coconut shell, coffee grounds, protein etc. These can alsobe used singly or as a mixture of two or more thereof.

The method of mixing and kneading the lactic acid-based resin (componentB), the aliphatic polyester having an aliphatic unsaturated bond(component A), a polymerization initiator and/or a sensitizer, and ifnecessary another modifier includes, for example, a method that involvesuniform mixing with a high- or low-speed stirrer and subsequentmelt-kneading with a single- or multi-screw extruder having sufficientkneading performance, and a method of mixing and kneading at the time ofmelting.

Mixing and kneading may be carried before molding of a molded article,or mixing and kneading may be carried out at the same time of molding.When mixing and kneading are carried out before molding, the resincomposition is usually preferably in the form of pellets, bar, powderetc.

[Non-Stretched Molded Article]

In a preferable embodiment, the resin composition used in the presentinvention comprises the components A and B crosslinked to increase melttension.

Accordingly, a molded article requiring high melt tension at the time ofmolding can be preferably obtained. Examples of the molded articleinclude an inflation film, a molded laminate product (paper lamination,aluminum lamination etc.), foam etc.

[Stretched Molded Article]

Regardless of whether the molded article obtained in the presentinvention is stretched or not, the molded article is stretched in 1.1-to 15-fold particularly in at least a monoaxial direction, whereby notonly flexibility but also heat resistance and strength can be improved.The resin composition used in the present invention has improvedcompatibility between the component (A) (for example the aliphaticpolyester having an aliphatic unsaturated bond) and the component (B)(for example the lactic acid-based resin) by crosslinking reaction, andis thus excellent in moldability in stretching orientationcrystallization and prevents bleeding of the component (B) during andafter stretching.

Stretching is carried out at a temperature of from the glass transitiontemperature (Tg) to the melting point of the lactic acid-based resin,preferably at a temperature of (Tg +5° C.) to (Tm −20° C.), morepreferably at a temperature of (Tg +10° C.) to (Tm −40° C.). When thestretching temperature is lower than Tg or higher than Tm, stretching ishardly conducted.

Examples of the molded article stretched in at least a monoaxialdirection include a film, sheet, tape yarn, (mono, multi) filament,nonwoven fabric, and stretched blow molded article, and any of thesemolded articles can be produced stably according to the presentinvention. The method of producing the molded article according to thepresent invention is not particularly limited and can use a knownmolding method.

[Physical Properties of Film and Sheet]

The film and sheet obtained in the present invention have the followingphysical properties.

The haze of the film or sheet is 5% or less, preferably 3% or less, morepreferably 2% or less. The tensile modulus of elasticity is 3000 MPa orless, preferably 2500 MPa or less, more preferably 2000 MPa or less. Thebreaking strength is 50 MPa or more, preferably 70 MPa or more, morepreferably 80 MPa or more. The elongation at breakage is 100% or more,preferably 150% or more, more preferably 200% or more.

When the film and sheet obtained in the present invention after beingleft at 23° C. in 43% RH atmosphere for 30 days is visually checked forbleeding of the plasticizer on the surface of the film, no plasticizerbleeding is observed. That is, no plasticizer bleeding occurs just aftermolding or with time, and flexibility and transparency do not change.

APPLICATION EXAMPLES

Molded articles produced by the invention, such as film, sheet, tapeyarn, (mono, multi) filament, nonwoven fabric, stretched blow moldedarticle, inflation film, laminate molded article and foam can be usedpreferably as various packaging films for food, electronics, medicine,chemicals, cosmetics etc. and as various materials used in agriculture,civil engineering and marine products industry, such as shopping bag,shrink film, garbage bag, compost bag, food/confectionary packagingfilm, food wrapping film, cosmetic/perfume wrapping film, diaper,sanitary napkin, wrapping film for pharmaceutical preparations, wrappingfilms for chemicals, wrapping film for application of chemicals forstiff neck and sprain, agricultural/horticultural film, wrapping filmfor agrochemicals, film for greenhouse, fertilizer bag, wrapping band,packaging film for magnetic tape cassettes such as video tape and audiotape, packaging film for flexible disk (FD), plate-making film, adhesivetape, waterproof sheet, sandbag, building film, weed controlling sheet,plant net, etc.

EXAMPLES

Hereinafter, the present invention is described in more detail byreference to experimental examples. The evaluation methods used in theExamples are as follows:

(1) Weight-Average Molecular Weight (Mw)

The weight-average molecular weight of the aliphatic polyester having analiphatic unsaturated bond was evaluated by gel permeationchromatography (GPC) with polystyrene as standard under the followingconditions.

-   -   Unit: Shodex GPC system-11    -   Column: PL gel 5 μm MIXED-C (manufactured by Polymer Laboratory)    -   Column temperature: 40° C.    -   Solvent: chloroform    -   Concentration: 0.5% by weight    -   Injection volume: 20 μL    -   Flow rate: 1.0 mL/min.        (2) Glass Transition Point (Tg)

Determined in the range of −100 to 200° C. by a differential scanningcalorimeter (DSC-3100 manufactured by Mac Science)

-   -   Increasing rate: 10° C./min.        (3) Film Strength, Modulus of Elasticity, and Elongation

Determined in accordance with JIS K7127.

(4) Filament Strength and Elongation

Determined in accordance with JIS L-1013.

(5) Haze

Determined in accordance with JIS K-6714 by using a haze metermanufactured by Tokyo Denshoku.

(6) Drop Impact Test

A 1000-ml container was charged with 800 ml water and then dropped froma height of 1.5 m to a floor of concrete under the condition of anatmospheric temperature of 20° C., and the number of times the containerwas dropped until it was broken was determined. The dropping wasconducted 10 times at the maximum.

(7) Bleeding

A film of 10 cm in machine direction and 10 cm in width direction wasleft at 23° C. in 40% RH atmosphere for 30 days, and bleeding of aplasticizer on the surface of the film was visually checked. Evaluationcriteria are as follows:

-   -   ◯: no bleeding. Δ: slight bleeding. x: bleeding on the whole        surface.        (8) MFR

190° C., loading 2.16 kg

(9) Swell Ratio (SR)

(Strand diameter/D)² at the time of extrusion at 190° C. through anorifice (length L=3.00 mm, diameter D=0.50 mm), barrel diameter B=9.55mm, speed 10.0 mm/min. was determined as SR.

(Formation of the Resin Composition (AA) and Molding of a Film Using theSame—a)

Preparation Example a1

Production of an Aliphatic Polyester (Mw 21000, Polyester PA) having anAliphatic Unsaturated Bond

A separable flask equipped with a stirrer, a heater, a thermometer and anitrogen line was charged with 151.7 g triethylene glycol, 141.8 gadipic acid and 3.5 g maleic acid. The compounding ratio of therespective components was 50 mol % triethylene glycol, 47 mol % adipicacid and 3 mol % maleic acid. 0.07 g titanium tetraisopropoxide and 0.1g hydroquinone were added thereto and reacted at 150° C. for 3 hours ina nitrogen stream, and while water was distilled away under reducedpressure at 2 kPa in the system, the mixture was further reacted at 150°C. for 20 hours. After cooling, the weight-average molecular weight ofthe resulting aliphatic polyester was 21000. The glass transition point(Tg) was −45° C.

Preparation Example a2

Production of an Aliphatic Polyester (Mw 56000, Polyester PB) having anAliphatic Unsaturated Bond

2.5% by weight of hexamethylene diisocyanate was added to polyester PAobtained in Preparation Example al and subjected to chain extensionreaction at 100° C. under reduced pressure conditions at 400 Pa for 2hours. After cooling, the weight-average molecular weight of theresulting aliphatic polyester was 56000. The glass transition point (Tg)was −40° C.

Preparation Example a3

Production of a Saturated Aliphatic Polyester (Mw 19000, Polyester PC)

A separable flask equipped with a stirrer, a heater, a thermometer and anitrogen line was charged with 151.7 g triethylene glycol and 150.9 gadipic acid. The compounding ratio of the respective components was 50mol % triethylene glycol and 50 mol % adipic acid. 0.07 g titaniumtetraisopropoxide and 0.1 g hydroquinone were added thereto and reactedat 150° C. for 3 hours in a nitrogen stream, and while water wasdistilled away under reduced pressure at 2 kPa in the system, themixture was further reacted at 150° C. for 20 hours. After cooling, theweight-average molecular weight of the resulting aliphatic polyester was19000. The glass transition point (Tg) was −50° C.

Preparation Example a4

Production of an Aliphatic Polyester (Mw 21000, Polyester PP) having anAliphatic Unsaturated Bond

A separable flask equipped with a stirrer, a heater, a thermometer and anitrogen line was charged with 150.2 g triethylene glycol, 141.8 gadipic acid and 3.9 g itaconic acid. The compounding ratio of therespective components was 50 mol % triethylene glycol, 48.5 mol % adipicacid and 1.5 mol % itaconic acid. 0.02 g titanium tetraisopropoxide and0.2 g hydroquinone were added thereto and reacted at 180° C. for 3 hoursin a nitrogen stream, and while water was distilled away under reducedpressure at 2 kPa in the system, the mixture was further reacted at 180°C. for 20 hours. After cooling, the weight-average molecular weight ofthe resulting aliphatic polyester was 21000. The glass transition point(Tg) was −54° C.

Examples a1 to a4

The aliphatic polyester (polyester PA or polyester PB) having analiphatic unsaturated bond obtained in Preparation Example a1 or a2 wasadded in an amount shown in Table a1 to polylactic acid manufactured byMitsui Chemicals, Inc. (registered trademark LACEA, grade H-100, Mw150000) and then kneaded at 200° C. for 5 minutes with a twin-screwkneader (Laboplast Mill 80C100 manufactured by TOYOSEIKIKOGYO CO., LTD).Kneading was terminated, and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane(trade name Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.)was added as a radical-generating peroxide in an amount of 0.3 part byweight based on the total amount of the resin, and then the mixture waskneaded again at 200° C. for 5 minutes. During kneading, an apparentincrease in temperature and viscosity was observed, indicating that thecrosslinking reaction proceeded. The resulting resin composition waspressed at 190° C., 12 MPa, with a heat pressing machine MP-WCH(manufactured by Toyo Seiki) to give a film of 200 μm in thickness.

Each film was transparent or slightly turbid, which was transparencywith no practical problem. When the surface of the film was visuallychecked, no bleeding of polyester PA or PB was recognized. When themodulus of elasticity of the film was measured by a method prescribedunder JIS K-7127, the modulus of elasticity was lower than that of thefilm composed exclusively of polylactic acid (Comparative Example a1),indicating that the film was evidently softened. The results are shownin Table a1. TABLE a1 Tensile Additive Peroxidase Evaluation of modulusof Polylactic acid (parts by (parts by pressed film elasticity (parts byweight) weight) weight) Turbidity*1 Bleeding (MPa) Example a1 90Polyester A 10 0.3 None ◯ 2500 Example a2 70 Polyester A 30 0.3 slightly∘ 1100 present Example a3 90 Polyester B 10 0.3 slightly ∘ 2700 presentExample a4 70 Polyester B 30 0.3 slightly ∘ 1400 present Comparative 100None 0 0.3 None ◯ 3500 Example a1 Comparative 70 Polyester C 30 0.3significant x 2700 Example a2*1Visual judgment

Comparative Example a1

Polylactic acid manufactured by Mitsui Chemicals, Inc. (registeredtrademark LACEA, grade H-100, Mw 150000) was kneaded at 200° C. for 5minutes with a twin-screw kneader without adding the aliphatic polyesterhaving an aliphatic unsaturated bond. Kneading was terminated, and2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (trade name Perhexa 25Bmanufactured by Nippon Oil and Fats Co., Ltd.) was added as aradical-generating peroxide in an amount of 0.3 part by weight based onthe total amount of the resin, and then the mixture was kneaded again at200° C. for 5 minutes. During kneading, an apparent increase intemperature and viscosity was not observed.

The resulting polylactic acid was pressed at 200° C. at 20 atmosphericpressure in a heat pressing machine to give a film of 200 μm inthickness. The film was a transparent and hard film having high modulusof elasticity. The results are shown in Table a1.

Comparative Example a2

The same procedure as in Example a2 was conducted except that thesaturated aliphatic polyester (polyester PC) obtained in PreparationExample a3 was used in place of the aliphatic polyester having analiphatic unsaturated bond. During kneading after addition of theperoxide, an apparent increase in temperature and viscosity was notobserved. The resulting resin composition was pressed at 200° C. at 20atmospheric pressure in a heat pressing machine to give a film of 200 μmin thickness. The film was opaque. When the modulus of elasticity of thefilm was measured, measurements were significantly varied. The surfaceof the film was sticky, and bleeding of the added polyester wasobserved. The results are shown in Table a1.

Examples a5 and a6

The aliphatic polyester (polyester PP) having an aliphatic unsaturatedbond obtained in Preparation Example a4 was added in an amount shown inTable a2 to polylactic acid manufactured by Mitsui Chemicals, Inc.(registered trademark LACEA, grade H-100, Mw 150000, grade H-400, Mw200000) and then kneaded at 200° C. for 5 minutes with a twin-screwkneader (Laboplast Mill 80 C100 manufactured by TOYOSEIKIKOGYO CO.,LTD). Kneading was terminated, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (trade name Perhexa 25B manufactured by Nippon Oil and Fats Co.,Ltd.) was added as a radical-generating peroxide in an amount of 0.3part by weight based on the total amount of the resin, and then themixture was kneaded again at 200° C. for 5 minutes. During kneading, anapparent increase in temperature and viscosity was observed, indicatingthat the crosslinking reaction proceeded. The MFR and SR of theresulting resin composition are shown in Table a2.

Comparative Examples a3 and a4

A resin composition was obtained in the same manner as in Examples 5aand a6 except that the radical generating initiator was not used. TheMFR and SR of the resulting resin composition are shown in Table a2.TABLE a2 Polylactic acid Polyester PP Peroxide (parts by weight) (partsby (parts by MFR H-100 H-400 weight) weight) (g/10 min.) SR Example a580 0 20 0.3 54.5 0.82 Example a6 0 80 20 0.3 22.1 1.81 Comparative 80 020 0 95.9 0.52 Example a3 Comparative 0 80 20 0 25.2 0.89 Example a4(Formation of the Resin Composition (AA) and Molding of a Film Using theSame)

Preparation Example b1

Production of an Itaconic Acid-Containing Lactic Acid Oligomer (Mw 2100,Polyester PD)

A separable flask equipped with a stirrer, a heater, a thermometer and anitrogen line was charged with 750.7 g of 90% L-lactic acid and 48.8 gitaconic acid. The compounding ratio of the respective components was95.2 mol % L-lactic acid and 4.8 mol % itaconic acid. The mixture wasreacted at 140° C. for 2 hours in a nitrogen stream, and the pressure inthe system was reduced gradually over 1 hour to 6.6 kPa, and while waterwas distilled away under reduced pressure at 6.6 kPa for 2 hours andthen at a pressure reduced to 1.3 kPa in the system, the mixture wasreacted for 7 hours. After cooling, the weight-average molecular weightof the resulting itaconic acid-containing lactic acid oligomer(polyester PD) was 2100.

Preparation Example b2 Production of Component (A)) Production of anAliphatic Polyester (Mw 22000, Polyester PE) having an AliphaticUnsaturated Bond

246.0 g polyester PD obtained in Preparation Example b1 was charged with525.6 g triethylene glycol, 10.9 g ethylene glycol, 496.2 g adipic acid,0.7 g hydroquinone and 0.07 g titanium tetraisopropoxide. Thecompounding ratio of the respective components was 31.0 mol % L-lacticacid, 1.6 mol % itaconic acid, 34.2 mol % triethylene glycol and 33.3mol % adipic acid. The mixture was reacted at 160° C. for 3 hours in anitrogen stream, then feeding of nitrogen was terminated, and whilewater and ethylene glycol were distilled away at a pressure reduced to1.3 kPa at 160° C. for 8 hours, then at 180° C. for 6 hours, at 190° C.for 17 hours and at 200° C. for 5 hours. After cooling, the resultingaliphatic polyester (polyester PE) had a weight-average molecular weightof 22000.

Preparation Example b3

Production of an Itaconic Acid-Containing Lactic Acid Oligomer (Mw 3500,Polyester PF)

A separable flask equipped with a stirrer, a heater, a thermometer and anitrogen line was charged with 750.7 g of 90% L-lactic acid and 24.4 gitaconic acid. The compounding ratio of the respective components was97.6 mol % L-lactic acid and 2.4 mol % itaconic acid. The mixture wasreacted at 140° C. for 2 hours in a nitrogen stream, and the pressure inthe system was reduced gradually over 1 hour to 6.6 kPa, and while waterwas distilled away under reduced pressure at 6.6 kPa for 2 hours andthen at a temperature increased to 160° C. at a pressure reduced to 1.3kPa in the system, the mixture was reacted for 12 hours.

After cooling, the weight-average molecular weight of the resultingitaconic acid-containing lactic acid oligomer (polyester PF) was 3500.

[Preparation Example b4 Production of Component (A)

Production of an Aliphatic Polyester (Mw 22000, Polyester PG) having anAliphatic Unsaturated Bond

198.8 g polyester PF obtained in Preparation Example b3 was charged with225.3 g triethylene glycol, 4.7 g ethylene glycol, 212.6 g adipic acid,0.3 g hydroquinone and 0.03 g titanium tetraisopropoxide. Thecompounding ratio of the respective components was 46.8 mol % L-lacticacid, 1.2 mol % itaconic acid, 26.4 mol % triethylene glycol and 25.6mol % adipic acid. The mixture was reacted at 160° C. for 4 hours in anitrogen stream, and while water and ethylene glycol were distilled awayat 200° C. at a pressure reduced to 1.3 kPa in the system, the mixturewas reacted for 18 hours. After cooling, the resulting aliphaticpolyester (polyester PG) had a weight-average molecular weight of 22000.

Examples b1 and b2 Production of Resin Composition (AA)

The aliphatic polyester (polyester PE or polyester PG) having analiphatic unsaturated bond obtained in Preparation Example b2 orPreparation Example b4 was added in an amount shown in Table bl topolylactic acid manufactured by Mitsui Chemicals, Inc. (registeredtrademark LACEA, grade H-100, Mw 150000) and then kneaded at 200° C. for5 minutes with a twin-screw kneader (Laboplast Mill 80C100 manufacturedby TOYOSEIKIKOGYO CO., LTD). Kneading was terminated, and2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (trade name Perhexa 25Bmanufactured by Nippon Oil and Fats Co., Ltd.) was added as aradical-generating peroxide in an amount of 0.3 part by weight based onthe total amount of the resin, and then the mixture was kneaded again at200° C. for 5 minutes. During kneading, an apparent increase intemperature and viscosity was observed, indicating that the crosslinkingreaction proceeded. The resulting resin composition was pressed at 200°C., 10 MPa, with a heat pressing machine MP-WCH (manufactured byTOYOSEIKIKOGYO CO., LTD) to give a film of 150 μm in thickness.

Each film was transparent. When the surface of the film was visuallychecked, no bleeding of polyesters PE and PG was recognized. When themodulus of elasticity of the film was measured by a method prescribedunder JIS K-7127, the modulus of elasticity was lower than that of thefilm composed exclusively of polylactic acid (Comparative Example a1),indicating that the film was evidently softened.

Example b3 Production of Resin Composition (AA)

50 parts by weight of the aliphatic polyester (polyester PE) having analiphatic unsaturated bond obtained in Preparation Example b2 were addedto 50 parts by weight of polylactic acid manufactured by MitsuiChemicals, Inc. (registered trademark LACEA, grade H-100, Mw 150000) andthen kneaded at 200° C. for 5 minutes with a twin-screw kneader(Laboplast Mill 80C100 manufactured by TOYOSEIKIKOGYO CO., LTD).Kneading was terminated, and 2,5-dimethyl-2,5-bis(t-butylperoxy) hexane(trade name Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.)was added as a radical-generating peroxide in an amount of 0.3 part byweight based on the total amount of the resin, and then the mixture waskneaded again at 200° C. for 5 minutes. During kneading, an apparentincrease in temperature and viscosity was observed, indicating that thecrosslinking reaction proceeded.

Example b4 Production of Resin Composition (BB) and Production of a FilmUsing the Resin Composition (BB)

40 parts by weight of the resin composition after crosslinking reaction(polyester PH) obtained in Example b3 were added to 60 parts by weightof polylactic acid manufactured by Mitsui Chemicals, Inc. (registeredtrademark LACEA, grade H-100, Mw 150000) and then kneaded at 200° C. for5 minutes with a twin-screw kneader (Laboplast Mill 80C100 manufacturedby TOYOSEIKIKOGYO CO., LTD). The resulting resin composition was pressedat 200° C., 10 MPa, with a heat pressing machine MP-WCH (manufactured byTOYOSEIKIKOGYO CO., LTD) to give a film of 150 μm in thickness.

The film was transparent. When the surface of the film was visuallychecked, no bleeding of polyesters PE and PH was recognized. When themodulus of elasticity of the film was measured by a method prescribedunder JIS K-7127, the modulus of elasticity was lower than that of thefilm composed exclusively of polylactic acid (Comparative Example a1),indicating that the film was evidently softened. (Haze, 0.7%; bleeding,◯; tensile modulus of elasticity, 2500 MPa).

Comparative Example b1

The aliphatic polyester (polyester PE) having an aliphatic unsaturatedbond obtained in Preparation Example b2 was added in an amount shown inTable b1 to polylactic acid manufactured by Mitsui Chemicals, Inc.(registered trademark LACEA, grade H-100, Mw 150000) and then kneaded at200° C. for 5 minutes with a twin-screw kneader (Laboplast Mill 80C100manufactured by TOYOSEIKIKOGYO CO., LTD). The resulting resincomposition was pressed at 200° C., 10 MPa, with a heat pressing machineMP-WCH (manufactured by TOYOSEIKIKOGYO CO., LTD) to give a film of 150μm in thickness.

Each film was slightly turbid. When the surface of the film was visuallychecked, polyester PE was slightly bled. When the modulus of elasticityof the film was measured by a method prescribed under JIS K-7127, themodulus of elasticity was slightly lower than that of the film composedexclusively of polylactic acid (Comparative Example a1), indicating thatthe film was somewhat softened. TABLE b1 Tensile Polylactic Polyester PEPolyester PG modulus of acid (parts (parts by (parts by Peroxide (partsEvaluation of film elasticity by weight) weight) weight) by weight) Haze(%) Bleeding (MPa) Example b1 80 20 0 0.3 4 ◯ 2511 Example b2 80 0 200.3 0.5 ◯ 2548 Example b4 80 20 0 0.3 0.7 ◯ 2500 Comparative 80 20 0 014.5 Δ 3362 Example b1

Example c1-1 Stretched Film

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 90:10:0.3 by a Henschel mixer and thenpelleted with a twin-screw kneader at a cylinder temperature set at 180to 210° C. The pellets were used to form a film with an extruderequipped with a dryer to give a film of 200 μm in thickness.Subsequently, this film was stretched 2.5-fold in length and 2.5-fold inwidth in an oven set at a temperature of 65 to 75° C. The sample wasexcellent in both film manufacturability and stretchability to give afilm stably. The physical properties of the resulting film are shown inTable c1.

Example c1-2

A stretched film was obtained by the same method as in Example c1-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PA, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 70:30:0.3.The sample was excellent in both film manufacturability andstretchability to give a film stably. The physical properties of theresulting film are shown in Table c1.

Example c1-3

A stretched film was obtained by the same method as in Example c1-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 90:10:0.3.The sample was excellent in both film manufacturability andstretchability to give a film stably. The physical properties of theresulting film are shown in Table c1.

Example c1-4

A stretched film was obtained by the same method as in Example c1-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 70:30:0.3.The sample was excellent in both film manufacturability andstretchability to give a film stably. The physical properties of theresulting film are shown in Table c1.

Example c1-5

Polylactic acid (LACEA H-400, Mw 200000, manufactured by MitsuiChemicals, Inc.), polyester PF obtained in Preparation Example b3, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were mixed in a weight ratio of 80:20:0.3and pelleted at 200° C. with a twin-screw kneader. The pellets were usedto form a film of 500 μm in thickness with an extruder equipped with anitrogen gas line (180 to 210° C.). Subsequently, this film wasstretched 3-fold in length and 3-fold in width with a batch twin-screwco-stretching machine set at a temperature of 70° C. and heat-treated ata temperature of 120° C. for 1 minute. The sample was excellent in bothfilm manufacturability and stretchability to give a film stably. Atransparent film with improvement in flexibility having a tensilemodulus of elasticity of 2300 MPa, an elongation of 115%, a breakingstrength of 102 MPa, and 0.7% haze was obtained. The evaluation ofbleeding was ◯.

Comparative Example c1-1

A stretched film was obtained by the same method as in Example c1-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 90:10:0.3.At the time of stretching, bleeding of polyester PC component on thesurface of the film was recognized.

The physical properties of the resulting film are shown in Table c1.

Comparative Example c1-2

A stretched film was obtained by the same method as in Example c1-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 70:30:0.3.At the time of stretching, bleeding of polyester PC component on thesurface of the film was recognized. The physical properties of theresulting film are shown in Table c1.

Comparative Example c1-3

A stretched film composed exclusively of polylactic acid was obtained bypelleting, film-making and stretching in the same manner as in Examplec1-5 except that polylactic acid (LACEA H-400, Mw 200000, manufacturedby Mitsui Chemicals, Inc.) only was used. The resulting film was atransparent but hard film with a tensile modulus of elasticity of 3500MPa, an elongation of 109%, a breaking strength of 120 MPa, and 1.0%haze. TABLE c1 Comparative Example Example c1-1 c1-2 c1-3 c1-4 c1-1 c1-2Resin Composition Polylactic acid 90 70 90 70 90 70 (parts by weight)Aliphatic polyester 10 30 10 30 10 30 (PA) (PB) (PA) (PB) (PC) (PC)Perhexa 25B 0.3 0.3 0.3 0.3 0.3 0.3 Evaluation Tensile strength [MPa] 5655 45 40 50 35 Tensile modulus of 2500 1200 2600 1600 3000 3300elasticity [MPa] Elongation [%] 20 250 100 180 10 80 Haze [%] 2.0 7.02.5 20 2.5 60 Bleeding ∘ ∘ ∘ ∘ x x

Example c2-1 Monofilament

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted with a twin-screw extruder under the condition of a cylindertemperature set at 180 to 210° C. The pellets were dried at 80° C. for10 hours and then spun at a temperature of 200 to 220° C. with a 65 mmspinning machine (dice diameter 40 mm, number of nozzle openings 90) togive a non-stretched filament and then stretched while being passedthrough a first water bath at a temperature of 70 to 80° C. and thenthrough a second water bath at a temperature of 90 to 100° C. (degree ofstretching in total=7.2-fold), followed by heat treatment through anatmosphere at 100 to 120° C. Spinning was stable, and troubles such asfilament cutting did not occur. The physical properties of the resultingfilm are shown in Table c2.

Example c2-2

A monofilament was obtained by the same method as in Example c2-1 exceptthat polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PB, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) wereused in a weight ratio of 70:30:0.3. Spinning was stable, and troublessuch as filament cutting did not occur. The physical properties of theresulting filament are shown in Table c2.

Comparative Example c2-1

A monofilament was obtained by the same method as in Example c2-1 exceptthat polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PC, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) wereused in a weight ratio of 70:30:0.3. At the time of spinning, filamentcutting occurred, and monofilament could not be produced stably.Bleeding of polyester PC was recognized. The physical properties of theresulting filament are shown in Table c2. TABLE c2 Comparative ExampleExample c2-1 c2-2 C2-1 Resin Composition Polylactic acid 70 70 70 (partsby weight) Aliphatic 30 (PA) 30 (PB) 30 (PC) polyester Perhexa 25B 0.30.3 0.3 Tensile strength [g/d] 56 55 50 Tensile modulus of elasticity[g/d] 250 1200 3000 Elongation [%] 20 250 10 Filament cutting No No YesBleeding ◯ ◯ X

Comparative Example c3-1 Multifilament

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted under the condition of a cylinder temperature set at 180 to210° C. in a twin-screw extruder. The pellets were dried at 80° C. for10 hours and then spun at a temperature of 230° C. with a dice having 20openings having a diameter of 0.2 mm with a dry spinning machineequipped with a dryer, to give a semi-stretched filament. The resultingfilament was stretched at a temperature of 80 to 100° C. and thermallyfixed at a temperature of 120 to 140° C. Spinning was stable, andtroubles such as filament cutting did not occur. The diameter of theresulting filament was 5d, and the strength was 4.0 g/d.

Example c3-2

A multifilament was obtained by the same method as in Example c2-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 70:30:0.3.Spinning was stable, and troubles such as filament cutting did notoccur. The diameter of the resulting filament was 5d, and the strengthwas 4.1 g/d.

Comparative Example c3-1

A multifilament was obtained by the same method as in Example b2-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were used in a weight ratio of 70:30:0.3.At the time of spinning, filament cutting occurred, and multifilamentcould not be stably produced. The diameter of the resulting filament was5d, and the strength was 3.8 g/d.

Example c4-1 Nonwoven Fabric

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted with a twin-screw kneader at a cylinder temperature set at 180to 210° C. The pellets were dried at 80° C. for 10 hours, then melted at210° C., melt-spun thorough a spinneret having 90 spinning openingshaving a diameter of 0.35 mm, taken off with an air sucker arranged 1300mm below the spinneret and accumulated on a moving capturing surface toform a web thereon. The take-off speed was about 3500 m/min. Then, theresulting web was passed between a metal embossing roll heated at atemperature of 80 to 100° C. and a smooth metal roll heated at the sametemperature, and heat-fused to give a nonwoven fabric. The fineness ofshort fiber of the resulting nonwoven fabric was 2.5 d, and the basisweight of the nonwoven fabric was 30 g/m².

Example c4-2

A nonwoven fabric was obtained in the same manner as in Example c2-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were mixed in a weight ratio of70:30:0.3. The fineness of short fiber of the resulting nonwoven fabricwas 2.5 d, and the basis weight of the nonwoven fabric was 30 g/m².

Comparative Example c4-1

A nonwoven fabric was obtained in the same manner as in Example c2-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were mixed in a weight ratio of70:30:0.3. At the time of spinning, filament cutting occurred, andspinning could not be conducted well under the condition of a take-offspeed of about 3500 m/min. Then, the take-off speed was reduced to about2600 m/min., and as a result, spinning could be achieved withoutfilament cutting, and a nonwoven fabric having a short-fiber fineness of3.0 d and a basis weight of 30 g/m² was obtained.

Example c5-1 Tape

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted with a twin-screw kneader at a cylinder temperature set at 180to 210° C. The pellets were dried at 80° C. for 10 hours and then formedinto a film of 100 μm in thickness with a 90 mm extruder of 1200 m indice width and 0.8 mm in lip gap at a temperature of 150 to 210° C.,equipped with a dryer. Then, the film was slitted into a tape of 6 mm inwidth, then stretched 5-fold at a temperature of 65 to 80° C. on a hotplate, and thermally fixed on a hot plate at 100 to 120° C. At the timeof stretching, no bleeding of the polyester PA component on the surfaceof the tape was recognized. The resulting tape had a width of 3.5 mm, athickness of 30 μm and a strength of 5.5 g/d.

Example c5-2

A tape was obtained in the same manner as in Example c2-1 except thatpolylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PB, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3. At the time of stretching, nobleeding of the polyester PB component on the surface of the tape wasrecognized. The resulting tape had a width of 3.5 mm, a thickness of 30μm and a strength of 5.4 g/d.

Comparative Example c5-1

A tape was obtained in the same manner as in Example c2-1 except thatpolylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PC, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3. At the time of stretching,bleeding of the polyester PC component on the surface of the tape wasrecognized. The resulting tape had a width of 3.5 mm, a thickness of 30μm and a strength of 5.0 g/d.

Example c6-1 Stretching Blow Molding

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted with a twin-screw kneader at a cylinder temperature set at 180to 210° C. The pellets were dried at 80° C. for 10 hours, then melted ata cylinder temperature of 140 to 250° C. and injection-molded into amold set at 0 to 50° C. in an injection stretching blowing moldingmachine, to give 40 g cold parison.

The resulting parison was softened by heating at 100° C. and transferredinto a bottle-shaped mold and blow-stretched 3.5-fold in length and3-fold in width with blown pressurized air at 1 MPa, to give acylindrical bottle having an aperture of 75 mm, a height of 100 mm andan internal volume of 1000 ml.

The thickness of the wall was 0.2 mm. This blown bottle was charged with800 ml water and dropped 10 times from a height of 1.5 m to a floor ofconcrete under the condition of an ambient temperature of 20° C., butthe bottle was not broken.

Example c6-2

A bottle was obtained in the same manner as in Example c2-1 except thatpolylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PB, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3. The thickness of the wall was 0.2mm. This blown bottle was charged with 800 ml water and dropped 10 timesfrom a height of 1.5 m to a floor of concrete under the condition of anambient temperature of 20° C., but the bottle was not broken.

Comparative Example c6-1

A bottle was obtained in the same manner as in Example c2-1 except thatpolylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PC, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3. The thickness of the wall was 0.2mm. This blown bottle was charged with 800 ml water and dropped 10 timesfrom a height of 1.5 m to a floor of concrete under the condition of anambient temperature of 20° C., and the bottle was not broken in the 3rddropping.

Example c7-1 Molding of a Paper Laminate

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer and thenpelleted with a twin-screw kneader at a cylinder temperature set at 180to 210° C. The pellets were dried at 80° C. for 10 hours, then kneadedand melted at 235° C. with an extruder equipped with a dryer and fitwith a T die of 1300 mm in width and 0.8 mm in lip width, and extrudedonto a craft paper (basis weight of 75 g/m² ) at a take-off speed of 120m/min. The film manufacturability was excellent without film cutting.The thickness of the resin layer of the resulting paper laminate was20±2 μm and the layer was excellent in thickness accuracy.

Example c7-2

A paper laminate was obtained in the same manner as in Example c7-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B, manufactured byNippon Oil and Fats Co., Ltd.) were used in the weight ratio of70:30:0.3. The film manufacturability was excellent without filmcutting. The thickness of the resin layer of the resulting paperlaminate was 20±2 μm and the layer was excellent in thickness accuracy.

Comparative Example c7-1

A paper laminate was obtained in the same manner as in Example c7-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B, manufactured byNippon Oil and Fats Co., Ltd.) were used in the weight ratio of70:30:0.3. With respect to film manufacturability, neck-in occurred,film cutting occurred in some cases, and a paper laminate could not bestably formed. The thickness of the resin layer of the resulting paperlaminate was 23±7 μm and the layer was poor in thickness accuracy.

Example c8-1 Inflation Molding

Polylactic acid (LACEA H-100PL, Mw 150000, manufactured by MitsuiChemicals, Inc.), polyester PA, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane (Perhexa 25B manufactured by Nippon Oil and Fats Co., Ltd.) weremixed in a weight ratio of 70:30:0.3 by a Henschel mixer, then molded ata resin extrusion temperature of 160 to 170° C. in an expansion ratio ofabout 2.4 in a 40 mm inflation molding machine (dice diameter 40 mm) toform an inflation film having a lay-flat width of 150 mm and a thicknessof 30 μm, and taken off. During and after molding, there was no bleedingof the polyester PA, and there was no blocking between the films.

Example c8-2

An inflation film was obtained in the same manner as in Example c7-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PB, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were mixed in a weight ratio of70:30:0.3. The film manufacturability was excellent without filmcutting. During and after molding, there was no bleeding of thepolyester PB, and there was no blocking between the films.

Comparative Example c8-1

An inflation film was obtained in the same manner as in Example c7-1except that polylactic acid (LACEA H-100PL, Mw 150000, manufactured byMitsui Chemicals, Inc.), polyester PC, and2,5-dimethyl-2,5-bis(t-butylperoxy) hexane (Perhexa 25B manufactured byNippon Oil and Fats Co., Ltd.) were mixed in a weight ratio of70:30:0.3. During and after molding, bleeding of the polyester PCoccurred, and blocking between the films was recognized.

Industrial Applicability

According to the present invention, there is provided a resincomposition suitable as a starting material of biodegradable materialmaintaining transparency, free of bleeding of a plasticizer and endowedwith flexibility.

The molded article of the invention is a molded article excellent inflexibility, mechanical strength, safety and decomposition and free ofbleeding of a plasticizing component and can thus be preferably used asa material widely in various packaging films for food, electronics,medicine, chemicals, cosmetics etc. and in various materials used inagriculture, civil engineering, buildings, marine products industry, andcompost materials. Even if the molded article is disposed of after use,it is not accumulated as industrial waste or domestic waste.

1. A resin composition (AA) comprising an aliphatic polyester oraliphatic polyamide (component (A)), a plastic having a melting point orglass transition temperature (Tg) of −10° C. or more (component (B)) anda radical generating agent (C), wherein the compounding ratio of thecomponent (A), the component (B) and the radical generating agent (C),based on the total weight thereof, is: 1 to 98.995% by weight of thecomponent (A), 98.995 to 1% by weight of the component (B), and 0.005 to5% by weight of the radical generating agent (C), and an aliphaticunsaturated polybasic acid (a) is contained in the polymer constituentof the component (A) and/or the component (B).
 2. The resin composition(AA) according to claim 1, wherein the component (A) is an aliphaticpolyester containing in the polymer constituent of the component analiphatic unsaturated polybasic acid (a), an aliphatic polyvalentalcohol (b) and an aliphatic saturated polybasic acid (c).
 3. The resincomposition (AA) according to claim 1, wherein the component (A) is analiphatic polyester containing in the polymer constituent of thecomponent 0.1 to 10 mol % aliphatic unsaturated polybasic acid (a), 10to 50 mol % aliphatic polyvalent alcohol (b), 0 to 49.9 mol % aliphaticsaturated polybasic acid (c) and 0 to 80 mol % aliphatichydroxycarboxylic acid (d).
 4. The resin composition (AA) according toclaim 1, wherein the component (B) is at least one member selected fromthe group consisting of polylactic acid, polyglycolic acid, lacticacid-glycolic acid copolymer, polyhydroxybutyrate, polyhydroxyalkanoate,polybutylene succinate, polyvinyl alcohol, cellulose acetate,polyethylene succinate, polycaprolactone, polybutylene succinate adipatemodification, polybutylene succinate carbonate modification,polybutyrene adipate/terephthalate, and copolymers and mixtures thereof.5. A resin modifier comprising the resin composition (AA) described inany one of claims 1 to
 4. 6. A resin composition (BB) comprising 1 to50% by weight of the resin composition (AA) described in any one ofclaims 1 to 4 and 50 to 99% by weight of a biodegradable resin (D). 7.The resin composition (AA) or (BB) according to any one of claims 1,which comprises a component subjected to crosslinking reaction.
 8. Amolded article comprising the resin composition (AA) or (BB) describedin any one of claims 1 to
 4. 9. A film having a haze of 2% or less, atensile modulus of elasticity of 2600 MPa or less, a breaking strengthof 70 MPa or more and an elongation at breakage of 100% or more,comprising a resin composition containing at least 50% by weight ofpolylactic acid.
 10. The resin composition (AA) or (BB) according toclaim 6, which comprises a component subjected to crosslinking reaction.11. A molded article comprising the resin composition (AA) or (BB)described in claim 6.